A smart entry system has been recently applied to a vehicle door lock system. This smart entry system detects the behavior of the user of the vehicle, such as approaching to the vehicle for opening the door or getting off the vehicle and executes automatic door locking or unlocking operation in response to such detected user's behavior. In more detail, the smart entry system detects the user's door locking and unlocking operation based on the user's operation of a door handle provided on the door of the vehicle. For example, according to this system, the door lock is released when the user outside the vehicle approaches his or her vehicle and touches the door handle with a hand for opening operation.
The behavior of the user of the vehicle, such as approaching to the vehicle or getting off the vehicle can be recognized by a communication between a hand carried device (such as a remote control), which a user of a vehicle carries with him or her, and a vehicle inside device. The radio wave communication is usually made through a bar antenna provided on the door handle of the vehicle. One of such bar antenna devices is disclosed in a Japanese Patent 2001-358522 A (in columns 12 through 39 and FIG. 1 or 2) or another Japanese Patent 2004-176343 A (in columns 44 through 46 and FIG. 1). According to the first publication (Japanese Patent 2001-358522 A), the disclosed bar antenna includes a ferromagnetic core portion and a bobbin enclosing the core portion and carrying a coil thereon. Both core and the bobbin are housed in a housing case and sealed within the housing case by a potting agent or the like. Accordingly, the anti-water (water resistance) performance is very high due to the sealed structure. However, solidification has to be made after filling the potting agent in the housing case. This will increase a manufacturing process, which eventually increases the manufacturing cost. According to the second publication (Japanese Patent 2004-176343 A), the bar antenna includes a rectangular solid ferrite and a vehicle use wire harness wound directly around the ferrite. This antenna structure is very simple in use structure by only a ferrite and a covering wire harness. This antenna structure also is superior in anti-water performance. This is because the structure has no connecting portions, just extending the wire harness for connection purpose. However, the structure may be unstable in antenna performance unless the ferrite and the wire harness are securely fixed. In order to securely fix the two members, a heat forming process is used to fix the harness on the ferrite core by plasticity deforming the wire harness by applying heat. This can stabilize the wire harness to the ferrite, but it needs extra processing, such as a heat processing, which eventually increases the manufacturing cost.
It is therefore, an object of the present invention to provide a bobbin for a bar antenna which can be assembled in simple way with less number of manufacturing process.
It is another object of the invention to provide an improved bar antenna using the improved bobbin in simple way with less number of processing.
It is still further object of the invention to provide a door handle for a vehicle having a high durability using the improved bar antenna in simple way with less number of processing.